Thread: Problems using a function

Code:

#include <stdio.h>
#include<strings.h>
#include<windows.h>

void locate(short x, short y) ;
void remove_scrollbar(void);
void makeFrame(void);
char security();

int main(void)
{
    remove_scrollbar();
    makeFrame();
    
    locate(5,4);
    char str[5] = security());
    locate(10,10);
    printf("%s", str);
    
    locate(2,27);
    printf("  Press enter to leave the program ");
    getchar();
    return 0;
}

    char security(void)
    {
        char out[5];
        locate(5,2);
        printf("Enter security code: ");
        scanf("%4d", &out);
        return out;
    }

I am wanting to use a value established in the function. Nothing but errors. Please help.

Originally Posted by Salem

You can't return an array.

Try

Code:

void security(char []);
int main(void)
{
    char str[5];
    security(str);
    return 0;
}
 
    void security(char str[])
    {
        printf("Enter security code: ");
        scanf("%4s", str);
    }

Thank you. However, my problem is passing a value back to main () and doing things, in main(), with the passed back value.

Surprise!
So void foo(char[]) means that the parameter given foo, becomes a static?
I thought that void foo means there is no return value.
What then is the use of char* foo(...) ?

Yes - I believe it was you who gave me examples with char* - I have looked at your code and also put it in with my notes for further reference. The problem at hand is creating a value in a called function, passing that value to main(0) and subsequently doing things with that value in main().

I have learned that one can either pass by pointer or by address, but how does parameter become a returned value, without getting static when the foo is void?

Originally Posted by Salem

That IS passing the value back to main.

Try it, examine the value of str after calling the function.

Is the pass back occurring by means of scanf - does the response to scanf result in placement of the value in memory, leading to the value becoming available in main() also?

What book are you using to learn C? A good book would explain the various methods to pass values to and from functions much better than what can be shown in a forum.

Do you know that there are multiple ways to pass a variable into a function? Ie: pass by value and pass by reference (a reference is a pointer in C).

Do you know that the function return value is not related to any parameter (unless you physically "return" a variable that is a parameter)?

Originally Posted by jimblumberg

What book are you using to learn C? A good book would explain the various methods to pass values to and from functions much better than what can be shown in a forum.

Do you know that there are multiple ways to pass a variable into a function? Ie: pass by value and pass by reference (a reference is a pointer in C).

Do you know that the function return value is not related to any parameter (unless you physically "return" a variable that is a parameter)?

Yes that was my premise, but it is happening differently in the example being discussed (qv), and that is exactly what is puzzling me.